In a combustion system where a combustion device, for example, a pyrolysis furnace is used to pyrolyze waste or such to obtain an oil, superheated steam is used as an auxiliary heat source.
For example, a first known method uses a process for regenerating waste comprising charging waste into a carbonizing and gasifying furnace downwardly inclined together with superheated steam from the inlet side to the outlet side and pyrolyzing and carbonizing the waste without causing combustion by indirectly heating the waste in a state blocked from air by an electric heater in the carbonizing and gasifying furnace and at the same time, the amount of deposition of the carbonized material in the furnace being increased toward the outlet side and water-gas-shift reaction being caused by the heat to produce a dry distillation gas mainly containing hydrogen and carbon monoxide, and converting the dry distillation gas to liquid fuels by using a Fischer-Tropsch catalyst in order to provide a waste regeneration method and a waste regeneration system for small-to-medium-sized facilities, capable of efficiently and simply carrying out gasification and gas reforming of solid waste simultaneously with carbonization of the wastes m one furnace and capable of readily controlling calorie and stably carrying out gasification and efficiently regenerating a carbonized material, a useful gas and a liquid fuel even if the apparatus is small-scale.
Superheated steam, which is generally produced by heating water to about 100° C. by a boiler, and then further superheating the boiled water to a prescribed temperature by a super heater, is send as a high temperature gas to a pyrolyzer, which is a combustion device, to be used as a carrier gas or an auxiliary heat means.
At this time, a boiler utilizing an oil such as heavy oil as a heat source or an electrical heating boiler is used as a boiler.
In this case, water supplied from a water source having a normal room temperature is heated to about 100° C. by consuming a considerable amount of energy.
In order to lower a temperature of high-temperature exhaust gas within a limit of the heat resistance of a latent heat recovery heat exchanger formed of titanium without using a heat exchanger for a high temperature while effectively utilizing the sensible heat of the high-temperature exhaust gas, a second known method discloses that the high-temperature exhaust gas is sprinkled at an inlet side or an outlet side of the latent heat recovery heat exchanger, the sprinkled water is heated by the heat of the exhaust gas to be water vapor, and the gas temperature is lowered. The water vapor generated by sprinkling water is condensed together with the original water vapor of the exhaust gas by taking advantage of characteristics of a latent heat recovery device. The increased condensation latent heat is also utilized for water supply to a boiler, for example, as high-temperature water.
However, the system disclosed in the first known method referenced above requires a large amount of energy to produce superheated steam, deducting the resulting oil from total energy, the energy amount rather becomes minus.
The technology disclosed in the second known method referenced above utilizes several hundred ° C., and the efficiency of this technology is not so high.
Particularly, in the case of combustion system where several tons of waste is daily liquefied, it is required to several hundreds litter of water at a normal temperature is boiled per hour and there is a disadvantage that a required amount of boiled water can be supplied to a super heater only by consuming a huge amount of energy.